At any
rate, in CC’s Secret, Charlie is shown arriving over the San Francisco Bay area in a Pan Am Sikorsky S-42 flying boat.
but at the time Secret was made and released (late 1935 – early 1936), Pan Am hadn’t begun passenger service between
Honolulu and SF. And Pan Am never used the S-42 for passenger service between these two points. (The Sikorsky didn’t
have the range to make this trip in its normal passenger configuration, although a special version—with fuel tanks in
lieu of passenger seating—was used to “prove” the trans-Pacific route, and for flight-route training purposes.)
The first Pan Am flying boat employed for passenger service on the Honolulu – San Francisco route was the Martin M 130.
Passenger service with this craft began in October of 1936 (mail/freight service began earlier).

Of course,
Charlie might have had special pull with Pan Am, and hitched a ride on an S-42
training flight.

As I
recall, a Martin M-130 correctly forms part of Charlie’s itinerary from Honolulu to Germany in CC at the Olympics (1937).In CC at Treasure Island, Charlie is shown traveling and arriving at San Francisco
in an M-130 (or a model of one in some scenes).By that time (1939) the newer
Boeing Model 314 flying boats were being added to the trans Pacific route, but the Martin craft were still being utilized.